The present invention relates to a method of mobile telecommunications and more particularly to a method of mobile telecommunications adapted to send an encoded voice signal.
Telecommunications using a mobile unit including a car phone, portable telephone, etc., has made rapid strides to meet the demands of the times. In mobile telecommunications, because a signal is received and sent through the medium of a radio wave, an error correction technology by which an error caused by noise can be corrected and an inputted signal can be regenerated faithfully is indispensable. Known technologies of error correction include a convolution encoding method, BCH method and RS (Reed-Solomon) method and the like. In the mobile telecommunications using a CDMA (Code Division Multiple Access) method, by introducing such error correction technologies therein, telecommunications of high quality have been implemented.
When information for error correction is added to a signal to be received or sent, information contents of the signal are increased. Increased information contents require more transmission power accordingly. However, in the case of mobile telecommunications using, for example, the CDMA method, the number of connections that can be made simultaneously within the same communication area (i.e., a communication area covered by one base station) is limited by maximum power that can be transmitted by a base station.
Therefore, in order to enable more simultaneous calls, information contents received or sent by each mobile unit must be minimized. This requirement is, however, contradictory to the requisite to assure the quality exceeding a specified level in the telecommunications of each mobile unit.
Moreover, if transmission power consumption can be reduced, mobile telecommunications time is able to be made longer because a mobile unit is allowed to be used until its battery has discharged all electricity.
The present invention has been made to solve problems described above and it is an object of the present invention to provide a method of mobile telecommunications to reduce transmission power required for sending with high error correcting capabilities maintained. According to the present invention, this object is achieved by methods described below:
1. A method of mobile telecommunications for sending a signal encoded after being sampled in a specified sampling cycle, with a header used for controlling added thereto, comprising a step of adding an error correcting code capable of error correction of only specified amounts of signals to specified amounts of signals placed most apart from the header of the encoded signal.
2. A method of mobile telecommunications for sending a signal encoded after being sampled in a specified sampling cycle, with a header used for controlling added thereto, comprising a step of adding a bit error correcting code capable of error correction of only specified amounts of signals to specified amounts of signals placed most apart from the header of the encoded signal.
3. A method of mobile telecommunications for sending a signal encoded after being sampled in a specified sampling cycle, with a header used for controlling added thereto, comprising a step of adding a burst error correcting code capable of error correction of only specified amounts of signals is added to the specified amounts of signals placed most apart from said header of the encoded signal.
4. The method of mobile telecommunications described in the above item 2 or 3 wherein an error correcting code capable of error correction of only data placed between headers neighboring each other and placed in an intermediate position apart from both headers neighboring each other is added to the data placed in the intermediate position between headers.
5. A method of mobile telecommunications for sending a signal encoded after being sampled in a specified sampling cycle, comprising steps of causing a plurality of kinds of distinguishable sending data to exist mixedly in the signal to be sent, of weighting each sending data depending on its importance and of improving more error correction capabilities of an error correcting code to be added to the sending data if the sending data is of higher importance.
6. A method of mobile telecommunications for sending a signal encoded after being sampled in a specified sampling cycle, comprising a step of adding, if voice data is contained in the signal to be sent, an error correcting code only to sending data being equivalent to a high order bit group obtained after an interleave processing.
7. A method of mobile telecommunications for sending a signal encoded after being sampled in a specified sampling cycle, comprising a step of adding, if data to be fed back when compression encoding is made is contained in said signal to be sent, an error correcting code only to sending data being equivalent to the feedback data.
8. A method of mobile telecommunications for sending a signal encoded after being sampled in a specified sampling cycle, comprising a step of placing, if voice data that has undergone processing of high order bits is contained in the signal to be sent, a high order bit group of said voice data contained in a sending frame and an error correcting code added to the said group near to a header while a low order bit group is placed apart from a header.